Intraoral radiographic x-ray film packets, also generally referred to as intraoral radiographic film packets or dental x-ray packets have been employed in dental offices to capture x-rays of a patient's teeth and gums. Such dental x-ray packets are disclosed in U.S. Pat. No. 6,309,101 (Bacchetta), U.S. Pat. No. 6,474,864 (Resch), U.S. Pat. No. 6,505,965 (McGovern), U.S. Pat. No. 6,579,007 (Bacchetta), U.S. Pat. No. 5,077,779 (Steinhausen), U.S. Pat. No. 4,922,511 (Gay), U.S. Pat. No. 4,912,740 (Liese, Jr.), all commonly assigned and incorporated herein by reference.
It is known in the art that heavy metals provide a shielding effect against various forms of radiation. Their effectiveness is associated with the size of their atomic nucleus or as is commonly referred in the art, their absorption cross-section. An effective heavy metal used to provide the shielding function in current medical and dental radiography is lead (atomic number 82). Lead has several advantages. The ease, with which it is formed, combined with its high density and relatively low cost make it a prime material to use in x-ray applications. Lead also provides high quality radiographic images by minimizing the image effects of backscattered radiation.
Yet, since certain heavy metals, like lead, are difficult to handle in certain applications and there is a perception that these heavy metals pose environmental issues, there exists an opportunity to not use lead for dental and medical radiographic applications. This opportunity exists even for applications wherein there is no patient contact with the lead, such as dental x-ray packets. Accordingly, there exists a need for a dental x-ray packet that does not employ lead for radiation shielding.
U.S. Pat. No. 6,459,091 (DeMeo) relates to a radiation protective garment having barium sulfate coated fibers. U.S. Pat. No. 4,670,658 (Meyers) is directed to a flexible sheet coated with barium sulfate that is used to shield or protect medical personnel during procedures where radiation backscatter can be a problem. While such systems may have achieved certain degrees of success in their particular applications, such materials are not suitable for shielding radiation in a dental x-ray packet because the required thickness to provide equivalent absorption would make the dental packet exceed ANSI standards and too rigid.
U.S. Pat. No. 6,042,267 (Muraki) discloses an intraoral x-ray image pickup apparatus which uses copper tungsten as an x-ray shielding member which is not suitable for the present application because of the necessary thickness to realize the same x-ray shielding effect as that of the lead member.
U.S. Ser. No. 10/734,861 titled INTRAORAL RADIOGRAPHIC DENTAL X-RAY PACKETS HAVING NON-LEAD RADIATION SHIELDING by McGovern et al, filed on Dec. 12, 2003, commonly assigned and incorporated herein by reference, is directed to a dental x-ray film packet which does not employ lead for radiation shielding.
The company Hanshin Technical Laboratory, Ltd. of Japan advertises a “Dental X-ray film and Daylight” processing system product which employs an “Instant Film” such as the DIF size 2 (30×40 mm), the DQD monobath solution for rapid development of the “Instant Film” in conjunction with a “Pusher” fixed volume injector with a nozzle that attaches to the top of the “DQD” bottle. Hanshin claims that diagnosis can be done in 30 seconds or more when using this system. As best understood by Applicant through Applicant's experimentation, Hanshin's dental packet has an outer envelope including a first layer which is a non-black colored layer comprising polyvinyl chloride (PVC) and a second layer which is a black PVC layer containing lead oxide in an amount intended to provide radiation shielding of a film chip. The layer containing the lead oxide is an inside layer, that is, the lead oxide containing layer does not come into direct contact with a patient.
The present invention is directed to a dental x-ray packet which does not employ lead for radiation shielding, and such radiation shielding material is sufficiently malleable/formable so as to be incorporated into a dental x-ray packet, yet provide for comfortable operation when used by a patient, and still minimize the image effects of backscattered radiation.